protected Scorer(Similarity similarity) 
{
    this.similarity = similarity;
}

Constructs a Scorer.

Parameters:

similarity - The Similarity implementation used by this scorer.

 abstract public Explanation explain(int doc) throws IOException
Returns an explanation of the score for a document.

When this method is used, the #next() , #skipTo(int)  and
#score(HitCollector)  methods should not be used.

 public Similarity getSimilarity() 
{
    return this.similarity;
}

Returns the Similarity implementation used by this scorer.

 abstract public float score() throws IOException
Returns the score of the current document matching the query.
Initially invalid, until #next()  or #skipTo(int) 
is called the first time.

 public  void score(HitCollector hc) throws IOException 
{
    while (next()) {
      hc.collect(doc(), score());
    }
}

Scores and collects all matching documents.

 protected boolean score(HitCollector hc,
    int max) throws IOException 
{
    while (doc() <  max) {
      hc.collect(doc(), score());
      if (!next())
        return false;
    }
    return true;
}

Expert: Collects matching documents in a range. Hook for optimization. Note that #next() must be called once before this method is called for the first time.